New and Notable

HERS Index Making News in Florida

The Multiple Listing Services (MLS), owned and operated by the Realtor Association, is an important tool for the real estate industry. Real estate agents use the MLS to locate properties in the market that meet the home buyers’ needs, and appraisers use the service to find comparables for developing the appraised market value of a home. If a feature does not appear in the MLS, it's basically hidden from the real estate market, which is why the recent decision to list the HERS index in Gainesville, Florida’s, MLS is big news.

The Gainesville MLS now lists a home’s HERS index score prominently in its report. What’s more, The Gainesville Sun published a front-page story, “More Homebuyers Willing to Pay for Green Features,” in its May 30, 2012 edition. “Real estate professionals say their experience anecdotally is that green- and budget-conscious buyers are willing to pay more for a house with energy-efficient features,” the article notes. “But determining what those features are worth to a home's value has proven difficult for appraisers armed with limited data.”

The article quotes Dave Gibbs of Coldwell Banker M.M. Parrish Realtors as saying that this information will “help Realtors more easily find homes with the green features that buyers are interested in and help appraisers compare sales data.”

This action on the part of the Gainesville MLS should serve as a model for other MLS listing services to start including easily understood information on the energy performance of a home. In Gainesville, a great deal of credit must go to local rater Ken Fonorow of Florida H.E.R.O., who has tirelessly advocated the use of the HERS index to the housing industry.

Berkeley Lab Assesses Residential Cooking Exhaust Hoods

Cooking exhaust hoods designed for home kitchens vary widely in their ability to capture and vent away the air pollutants generated by the gas burners on cookstoves, according to a study by two Lawrence Berkeley National Laboratory (LBNL) scientists. The capture efficiency of the seven representative devices they tested ranged from less than 15% to more than 98%. The study, by Woody Delp and Brett Singer of LBNL’s Environmental Energy Technologies Division, measured the exhaust hoods’ pollutant capture efficiency, the sound level generated by their fans, and their airflow. Cooking exhaust hoods vent such pollutants as CO, nitrogen oxides, formaldehyde, and fine particulates such as soot generated during cooking.

While the exhaust hoods that Delp and Singer tested varied widely in performance, they found that all the exhaust hoods did a better job of capturing pollutants generated by the two back burners of a four-burner stove than of capturing pollutants generated by the front burners.

“Even a moderately effective exhaust hood can reduce a stove user’s exposure to pollutants,” says Delp, “and using the back burners preferentially over the front burners helps reduce exposure even more.” However, the findings of this study suggest that design improvements can increase the ability of hoods to capture pollutants and reduce their noisiness without increasing their energy use.

The study addresses the pollutants emitted by burners on the stove, but the process of cooking foods—for example by frying or stir frying—also generates pollutants. Delp and Singer have not confirmed that their results are applicable to pollutants generated by cooking foods, but they believe that they are; and they have funding for a follow-up study to confirm that the test method used in this study can be used to assess the capture of pollutants from the cooking process. They are also working on developing test standards that would allow appliances to be rated for their performance in capturing pollutants.

Pollutant capture efficiency is the percentage of pollutants at the cooking surface captured by the exhaust hood. Delp and Singer selected models that are representative of the different types of under-cabinet exhaust hood available in the U. S. retail marketplace. Several hoods covered only part of the two front burners of the gas stove. The coverage of one hood, a premium model, extended out beyond the front burners. Some of the models had grease screens or metal covering their bottoms, and some were open underneath. Two were Energy Star rated. The seven ranged in price from $40 for an economy model to $650, with most falling in the $250–350 range.

The results showed that exhaust hoods varied widely in their performance, and that while most of the hoods performed relatively well at venting exhaust gases, most did not do everything well. Some hoods had high capture efficiencies, some were very quiet, and some were energy efficient, but rarely were all three qualities captured in a single exhaust hood.

The hood with the highest capture efficiency, exceeding 80% for front burners, was a large open hood that covered most of the front burners, but it generated sound levels too high for normal conversation. The capture efficiency of hoods meeting Energy Star criteria was less than 30% for front and oven burners.

“These results suggest ways that manufacturers can improve the performance of their products,” says Singer. “Improving the geometry of the hoods—by making them deeper front to back and using methods such as recessed grease traps, blower entries up inside the hood, and better fans and motors will improve their capture efficiency.”

App Alert: ResVent 62.2

ResVent 62.2, available for the iPhone, iPod touch, and iPad, has been released by R.J. Karg Associates of Bethel, Maine. This mobile application calculates the minimum whole-building ventilation requirements of ASHRAE 62.2, “Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings.”

ResVent 62.2 features a choice of ASHRAE 62.2-2007 or 62.2-2010, for new or existing dwellings. It features reports that you can view on your hardware or e-mail; slider controls for easy data entry; a range control of sliders; a picker wheel for easy selection of over 200 weather locations; a fan run-time calculator; a special math-on-the-fly feature; and a comprehensive Help screen. It can calculate the infiltration credit and the alternative compliance supplement for existing homes.

learn more

For more information on the application and to view its instruction manual, visit www.karg.com.

This application allows residential energy professionals to comply with the ventilation requirements of BPI’s “Home Energy Auditing” standard, DOE/NREL’s “Workforce Guidelines for Home Energy Upgrades,” and EPA’s “Healthy Indoor Environment Protocols for Home Energy Upgrades”—all of which call for compliance with ASHRAE 62.2.

R.J. Karg Associates has been writing software for compliance with the ASHRAE ventilation requirements for over 12 years. The ResVent 62.2 app can be downloaded at the iTunes store for $19.99.

Century Club Award Winners

In March, DOE announced the 2011 Home Performance with Energy Star Century Club Contractors. This Century Club award recognizes companies nationwide that have improved the energy efficiency of more than 100 homes in the past year. These contractors participate in the Home Performance with Energy Star program. Following are the names of this year’s winners:

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